Safety pipe joint



Filed may 5, 1945 May 36, 95@ F. M. THURSTON ET A1.. 2,508,3@6

SAFETY PIPE JOINT 2 Sheets-Sheet l RANK MTHU RSTQN. CMORGE E JUSTUCE. INVISN'IORS May l5, i950 F. M. THURSTON ET AL 2,598,3@ I

SAFETY PIPE JOINT FRANK M THURSTON `1li/l GEORG E JUSTIC E INVENTORS Patented May 16, 1950 SAFETY PIPE JOINT vFrank M. Thurston and George E. Justice, Houston, Tex., assignors to Houston Oil Field Material Company, Inc., Houston, Tex., a corporation of Delaware Application May 5, 1945, Serial No. 592,180

The invention relates to what is generally known as a' safety joint and constitutes a pipe connection rto'be inserted into a string of pipe. The present application is a continuation in part of our previous safety joint application for patent, Serial Number 419,436, filed November 17, 1941, which became abandoned.

A safety joint is usually provided in `a string *of pipe so' as to assure the operator that when he attempts 'to unscrew the portion on one side of the safety joint from the portion on the other side, that the unscrewing or disconnecting 'of the pipe will occur at the safety joint rather than at some other threaded connection.

Safety joints are usually utilized in drill pipes used in the rotary method in drilling wells and must be of very sturdy construction so as to transmit the same torque which is applied to the drill Vpipe on the one hand and to carry the load of the pipe, drill bit, and drill collar positioned be` vlow it on the other hand. These conditions must tion to provide a safety joint which will release when under strain and through which the load of the pipe therebelow may be readily transmitted.

Another object of the invention is to provide a pipe joint which will have a large area of contact between the two members thereof so as to transmit the load below the joint.

Still another object of the invention is to provide a safety pipe joint having a buttress type of thread with a large substantially radial upper face so as to transmit the load without any wedging action which tends to increase the chances of the joint releasing.

Another object of the invention is to provide a safety joint wherein the threaded area is lled witha lubricant and sealed against the entry of mud or other foreign matter so as to facilitate the release of the joint.

A still further object ofthe invention is to provide a safety joint having a combination of a Vbuttress thread which will transmit the load without any wedging action and a stop shoulder itc limit the vtightening action of the joint.

s claims. (o1. 285-146) Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawings, wherein- Fig. 1V is a side elevation of the pin member. certain parts shown in "section and illustrating the construction thereof.

Fig. 2 is a vertical sectional view through the pin member, illustrating the arrangement of the threads and internal structure.

Fig. 3 is a vertical sectional view of the tool made up and in operating position.

Fig. 4 is :a side elevation illustrating the arrangement of the stop shoulder when the pin member is approximately one-quarter of a turn from stopping position.

VIn Fig. 1 the pin member 2 is in the form of a section of pipe having the passage 3 therethrough and the internal threaded area 4 to receive the next section of pipe of the drill stem or other string Yof pipe into which the safety joint is to be incorporated.

This pin member 2 has the principal body portion 5 thereof reduced in diameter to provide a circumferential surface 6 which is defined by a shoulder 'I best seen in Fig. 4. This shoulder is circumferential in that it runs around the entire body but it has the two upper inclined surfaces 8 and the two downwardly inclined surfaces 9 which merge in the upper apex I0 and the lower apex I I.

The circumferential surface 6 is recessed at I2 and a packing or seal ring I4 is disposed in this recess. This sealring may be the lip construction I5 at each end thereof so that pressure flow ing against the ring will tend to force it to sealing position against the base of the recess and against any external surface.l I

The surface 6 then merges with the threaded area 2U which is of particular construction in that it is made' up of a coarse buttress type of thread wherein each thread has a substantially radial upper surface 2|, a rounded corner 22 and ticular attention is directed to the fact that the The box member 30 best-seen inFig."2 has thev the box member so that the safety joint serves as a driving connection in the string of pipe.

One of the substantial advantages of the present safety joint is the fact that the torque is transmitted by the shoulder 1 while the load is transmitted by the buttress thread. In this manner the threaddoes .not'havetoftransmit any torque and the shoulder .doesv nothave. to transmit any load. Each performs its own function and is constructed for that purpose.

.In event the joint is to be unscrewed the operator merely turns the upper portion of the pipe' inV a counter-clockwise direction and the upper circumferential surface-3| thereof which.

is directly above the threaded area 32. This threaded area 32 is the complementary thread portion to the thread on Hthe pin. member 2 in that it has the at upper surface 2 l, the rounded corner 22, and the tapered portion .23 and the short cylindrical area 24. These match identicallywithrthe. male portions Vvorrthe pin members -sothat as -seenin Fig.. 3 the joint maybe made up tightly to transmit the loadthrough the joint. Below the threaded area 32 in the pin member is a -recessf34 which isy reduced somewhat to pro- 1 Avide 'theilower circumferential area 35. This area is recessed at 3B to receive a seal ring 3l 'which Ais identical-*with the ringV I 4 on the pin member. .Thebox member has the lower threaded pin 39 which is arranged to connect to the f pine string therebelow.

The safety jointis ,shown inFig. 3 as having .been'madeupand inoperative position, but of course the ladditional pipe to `be screwed into `the .upper-.and lower 'ends respectively is not shown.

In making upfthe-jointto assume the vposition 'of-Fig.'-3, thezpin member of Fig. 1 is inserted in l the box member of Fig. 2 and rotated to the pol sition of Fig. 4. During this vmovement the surface 2t` moves fto the surface 35 so that the seal ring 31 bears against the circumferential surface 2B as .bestseen in thelowerportion of Fig. 3. .Above the threaded area the circumferential sur- -face 6 moves into-the circumferential surface 3| of the pin member sov that the-seal ring I4 bears against such-surface 3| as best seen in the upper .portion of Fig. 3. AIn this position the packing or I sealingrings are conned and any pressure fromeither the-threaded area between the seal rings or from either above or below the seal rings fis resisted-andtends to expand the seal rings to prevent a ow of fluid thereby.

It seems 'obvious that the parts of the threaded areas may be thickly coated with lubricant as .theyfare inserted in position so that any space between the-seal rings will be substantially filled with lubricant or if desired a suitable injection Vinlet'may be provided for the introduction of lu- -bricant or sealingl material. The presence of such material in the'jointpreventsthe entrance'of any foreign matter such `as sand oranyV abrasive material which might deter the releasing of the joint.

The joint isY nowfully made .up by turning the parts a 'quarter' Vfa turnffrom the `position lof `lig. Also as to bring the shoulder 9 against acomplementaryfshoulder 49 on the upper end A9 of the pin member. vThe-shoulder 8 in a like man- Vner moves inwardly close tothe shoulder 8 lso *that there is .a complete :closureshown by the y'dotted line 4 l "inFig. 3.

This stopjshoulder` serves 'to prevent any further making upof thethreaded joint andserves to transmit the torquezfrom1 .the pin `member .to

joint will readily release and can be unscrewed Y.so that the operator knows that his pipe is releasing-atafdnite point. This safety joint is intended..and.does.release rather than the release of the threaded area such as 4 or 39 where the joint is fconnected to the adjacent sections of pipe.

Broadly the invention contemplates a safety joint-whichis'made ,upand ftransrnits torque Vwithoutv any --wedging action and-which can 4be readily unscrewed ywhile 'under a'strain or `carrying a loadbecause the threaded areas are not wedgedin position'by'such strain or load.

What is claimed'is:

l. A safety pipe joint comprisinga box member and a'pin member,'cooperating coarse threads in saidbox member and onsaid pin member, said -threads having a substantially radial upper face,

a rounded edge, a taperedlowerfface, `and a circular por-tion between :and vspacing adjacent threads so that .thejoint maybe readily unscrewed while under tension-and the radial upper face'serves to ltransmit'the-load-.through the joint :from one member-to the other.

2. AA lsafety-pipe jointA comprising abox' member and a'pin member, cooperating coarse threads in said box memberv and' on said pin member, said .threads having 'a substantially radial upper face, a rounded-edge, a tapered-'lower face,'and;a circular portion -fbetween and spacing adjacent threads -so `:that the joint may be readily'unscrewed while under tension and the radial upper faceserves to transmit the load'throughfthe jointfrom Aone Vmember to the-other, and complementary stop 'shoulders on -said members lto 4limit the tightening movement.

3. -A safety joint comprising complementary vbox and'pin members, saidbox beinginternally threaded with a coarse buttress type female thread having an Vupper at-load transmitting face, said pin having a complementary identical male thread,'saidf members eac-h having complementary circumferentialsurfaces at-each endfof the threaded area, an -annular recess in one of each pairof surfaces of ea-ch member, and a resilient lip type of seal ringin-eachrecess to be abutted by the complementarycircumferential surface so as to formaseabat each end of the threads-which is adaptedto-retain a-lubricant'in the joint.

FRANK` M. T-HURSTON.

GEORGE E.. JUSTICE.

REFERENCES CITED f vThe-following references'areY of'record in the file of--this patent:

UNITED STATES vPA'HNTS Number Name Date 646,597 `Bullock .Apn 3, 1900 y1,573,362 .Raber Feb. 23, 1926 1,5901357 Feisthamel June 29, 1926 2,196,966 .-rHammer, .Apr. 9, 1940 

